Mecha Man

A NES game built from scratch in 6502 Assembly.

Prerequisites

macOS

Install the cc65 toolchain (assembler + linker) via Homebrew:

brew install cc65

Verify the installation:

ca65 --version
ld65 --version

You will also need an NES emulator to run the ROM:

• Mesen — Recommended. Excellent debugging tools including a PPU viewer, memory inspector, and disassembler.
• FCEUX — Another solid option with built-in debugging.

Windows

Install the cc65 toolchain using one of these methods:

Option A: Pre-built binaries (simplest)

1. Download the latest Windows snapshot from cc65.github.io under "Windows Snapshot."
2. Extract the zip to a folder (e.g., C:\cc65).
3. Add the bin folder to your system PATH:
   • Search "Environment Variables" in the Start menu.
   • Under "System variables," find Path, click Edit, and add C:\cc65\bin.

Option B: Via MSYS2

pacman -S mingw-w64-x86_64-cc65

Verify the installation:

ca65 --version
ld65 --version

For an NES emulator on Windows:

• Mesen — Recommended.
• FCEUX

If you are using Windows without make available, see the Building without Make section below.

Project Structure

mecha-man/
├── hello.asm      # Assembly source code
├── nes.cfg        # Linker configuration (memory layout for the ROM)
├── Makefile       # Build automation
├── .gitignore
└── README.md

Building the ROM

Using Make (macOS / Linux / Windows with Make)

Build the ROM:

make

Clean build artifacts:

make clean

Building without Make

If make is not available (common on Windows), run the two build steps manually:

ca65 -o hello.o hello.asm
ld65 -o hello.nes -C nes.cfg hello.o

Step 1 (ca65) assembles the source code into an object file. Step 2 (ld65) links the object file into a final .nes ROM using the memory layout defined in nes.cfg.

Running the ROM

Open hello.nes in any NES emulator:

macOS:

open hello.nes

This opens the file with whatever application is associated with .nes files. You can also drag and drop hello.nes into your emulator window, or open it from the emulator's File menu.

Windows:

Double-click hello.nes if you have an emulator associated with the file type, or open it from the emulator's File > Open menu.

Expected output: White text reading "HELLO WORLD!" centered on a black background.

Learning Resources

• Classic Game Programming on the NES by Tony Cruise — The book this project follows alongside.
• NESdev Wiki — Comprehensive NES hardware and programming reference.
• 6502 Instruction Set Reference — Complete reference for every 6502 CPU instruction.
• ca65 Users Guide — Documentation for the assembler.